CompositesWorld
Issue link: https://cw.epubxp.com/i/944580
MARCH 2018 36 CompositesWorld FEATURE / In-situ Consolidated TPCs ALTERNATIVE, TWO-STEP APPROACH • Frames and stringers are stamped from AFP flat panels • Loaded into tools • Mated with pre-layed AFP skin • Assembly is vacuum-bagged and autoclave-cured. polymers, develop the crystalline lattice structure, which imparts their notable mechanical properties and chemical resistance, as they cool. Like Automated Dynamics, Accudyne's first work relied on hot gas torches and heated shoes. "One could almost say that Accudyne's work around in-situ consolidated TP parts began with DuPont," says Mike Smoot, VP sales and marketing at Accudyne Systems. Several Accudyne employees were part of DuPont's Advanced Materials Group in the 1980s and '90s. "During that time," he continues, "we developed a thermoplastic head and placed it on a standard filament winder. Infrared [IR] lamps heated the incoming tow, hot shoes guided the material onto the part, hot gas torches heated the laydown area and chilled pressure rollers cooled the molten polymer. Noncontact IR sensors measured the temperature of the incoming tow and laydown area, adjusting the thermal devices accordingly to stay within the required PEEK or PEKK process specifications." DuPont's work led to its participation in an early 1990s Defense Advanced Research Projects Agency (DARPA) program to build a 610-mm (24-inch) diameter, 16-mm (0.629-inch) thick ring-stiffened cylinder, using IM7 carbon fiber/APC-2 UD tape. Smoot says the ISC cylinder achieved <1% porosity and failed within 3% of its design load when tested underwater at 5,500 psi. is success opened other development opportunities for a variety of parts including rings and bearings for chemical processing, sonar shells, handheld rocket launch tubes, helicopter pitch links, and containment rings for high-speed permanent magnet rotors. From 1998 to 2012, Accudyne did extensive work in developing an in-situ laminator that could process either 76-mm (3-inch) wide tape or 12 ends of 6.35-mm (0.25-inch) tow. Initial effort focused on FIG. 2 FIDAMC ISC TPC curved panel Pictured here are the manufacturing steps developed for FIDAMC's in-situ consolidated curved panel with integrated stiffeners. Source | FIDAMC AFP layup flat panels, cut and stamp into stringers, place stringers into integrated fuselage panel tooling. AFP skin onto stringers, achieving in-situ consolidation. Completed, consolidated TPC demonstration part. Across the Atlantic, Automated Dynamics (Niskayuna, NY, US, now part of Trelleborg Group, Trelleborg, Sweden), began its first TPC project in 1985-86. "It was an SBIR [small business innovation research grant] funded by the US Army for devel- opment of a helicopter main rotor blade spar," says Automated Dynamics president Robert Langone. "In-situ consolidation was a focus from the beginning." A hot nitrogen gas torch was used to heat the thermoplastic to its melt temperature. A few years later, the company developed a heated roller for compaction. Quality further advanced when it acquired personnel and tech- nology from Imperial Chemical Industries (ICI) Composites, the original developer of Victrex polyetheretherketone (PEEK), also known as APC-2 in its unidirectional (UD) tape prepreg form, a material still in use today. "We were founded to sell machinery, but by the early 1990s we were producing in-situ consolidated cylin- drical parts every day," notes Langone. Automated Dynamics sold its first articulated arm-based ISC workcell to NASA Langley Research Center (Hampton, VA, US) in 1994, and by the late 1990s was fully immersed in industrial production of ISC parts for the oil and gas industry. ese included antenna shields, logging sleeves, plugs, pipes, pressure vessels and more, made from glass, aramid and/or carbon fiber (CF) and a range of matrix materials, including PEEK, polyethylene (PE), polypropylene (PP) and others. De Vries notes that Accudyne Systems Inc. (Newark, DE, US) also was an ISC pioneer, "the first to characterize the process window and develop a flexible compression head to keep pressure on the material as it cools." at was important because PEEK, polyetherketoneketone (PEKK) and PPS, as semi-crystalline It is difficult to achieve <1% void content in ISC TPC parts when incoming tapes have up to 20% void content.